Modern businesses, institutions, agencies, and other entities use software to help generate reports on which decisions are based. A report definition guides or influences data selection, layout, statistical calculations, and other computational processing, to help present data from a database or other data source in a form that helps decision makers.
Some report definitions include facilities for grouping data. Within data-oriented applications such as some query and reporting tools, for example, data can be grouped before being displayed to the user in a report. Grouping of data can serve purposes such as clustering related data, subtotaling, and identification or removal of duplicate data. Grouping can be performed over a single data field, such as grouping a list of customers by state. Grouping can also be performed over multiple nested data fields, such as grouping a list of customers by state and then within each state grouping the customers by gender.